The interior temperature of a fuel tank, such as an automobile fuel tank, rises and falls during the use of the vehicle. Vapor can be vented from the fuel tank and into a fuel vapor canister.
The U.S. Pat. No. 1,695,358 to Appleman, issued Dec. 18, 1928, is an example of a tank for storing a volatile liquid such as oil, which includes a vent and overflow opening adjacent its upper end for venting vapor. The Appleman patent provides no means for adsorbing the vapors.
The U.S. Pat. Nos. 2,278,192 to Cantacuzene, issued Mar. 31, 1942 and 2,472,622 to Savard, issued June 7, l949, disclose thermic processes and assemblies for recovering fuel vapor.
Copending U.S. Ser. No. 918,886, filed Oct. 15, 1986, which is a continuation-in-part of patent application Ser. No. 851,548, filed Apr. 14, 1986, and assigned to the assignee of the present invention discloses a fuel vapor storage canister which avoids releasing the fuel vapor to the atmosphere. The application discloses a system which vents the vapor to a canister having a bed that adsorbs and stores the fuel vapor. Specifically, the adsorptive material is an activated carbon.
It is an object of the present invention to increase the efficiency of storage of vapors by the canister.
It is another objective of the invention to increase the efficiency of the purging of fuel from the canister.